Conventional sacrificial anodes are employed in various metal structures, for example, hot water tanks, in order to prevent the corrosion of the tank. As the term indicates, the anode itself is depleted during its operational life to provide cathodic protection of the metal structure. Prior to this invention, these anodes were cylindrically-shaped rods of magnesium, zinc, or aluminum metal having a uniform diameter and containing a metal core of a strong conductive material, such as steel.
Applicants have found that in many applications, consumption of the anode is uneven and that the amount of corrosion protection varies in part as a function of the location of the anode. For example, tests have shown that approximately 90% of the anode activity occurs in the top and bottom third of a cylindrical, glass-lined, metallic hot water tank. On the other hand, only 10% of the anode activity occurs in the middle one-third of the tank.
The reason for non-linear consumption of the sacrificial anode is that larger amounts of cathode area requiring protection are located in the top and bottom areas of the tank. The non-linear consumption of the sacrificial anode therefore causes it to thin out more rapidly in the anode adjacent to the top and bottom sections of the tank. This requires replacement of the anode rod even though the central section of the rod remains usable. Failure to replace the anode will result in diminished anode protection, decreasing the effective life of the tank.
Accordingly, the present invention is related to a shaped anode formed from a plurality of extruded anode sections, and a method of forming the same.